This study was conducted to obtain the basic information for easily judgement to level of salinity stress of the reclaimed land. Rice varieties used were Nakdongbyeo and Chilsungbyeo. In seedling stage, 13 day-old seedlings were subjected to salt solution (0, 30, 60, 90mM) for 8 days. In reproductive stage, 30 day-old seedlings were transplanted 3 hills(3 seedlings /hill) per plastic pot (diameter 28depth 30cm). Salinity stress was given by immersing pot in the salt solution(sea water) with 4 concentrations(0, 30, 60, 90mM)for 8 days at booting stage. The stomatal resistance was increased with salinity concentrations. Salinity stress appeared to be more sensitive in seedling stage than in reproductive stage in each concentrations. The photosynthesis was decreased in salinity treatment. Salt-treated periods influenced unfavorably stomatal resistance in each stages. The leaf chlorophyll content was remarkably decreased by increasing salt concentrations. The absorption of Na+ and Cl￣ were increased as salt concentration in the culturing medium became higher, but there was no appearent difference in the absorption of K+, Mg++, and Ca++. The plant height and root length were decreased in salinity treatment. The inhibitory effect of salinity stress on root growth was more severe than in shoot growth. The stomatal resistance could have been used as bio-information.

The amount of maize being imported from other countries to meet the national demand are increasing every year. Regardless of the usage whether it is for silage or for human consumption, amount of seeds for farmers are ever being increased. In order to solve the problems arising from the seed import, a program for developing waxy hybrids with high quality was set up at the College of Agr., Chungnam National University. The main breeding targets for high quality waxy hybrids are focused on the pericarp thickness. In order to obtain basic information needed for developing hybrids with thin pericarp, six inbred lines all derived from open pollinated Korean waxy lines were diallel crossed. Results obtained indicate that waxy hybrids with thin pericarp can be developed by choosing proper parental lines. Of the six inbreds, Jewon inbred had utmost thin pericarp compared with other lines. Hybrids crossed with Jewon showed also thinner pericarp than other hybrids. However, Danyang which has thick pericarp showed thicker pericarp in hybrid combinations. Variance due to general combining abilities was greater than the variance due to the specific combining abilities, indicating that additive gene effects are more important. The pericarp thickness of waxy hybrid endosperm varied with the parts of pericarp. The germinal side of the pericarp is comparatively thinner than the abgerminal side. The upper part (crown) has thicker pericaip than lower part (tip) of the kernel.

This experiment was conducted to investigate the amount of natural crossing at varying isolation distance and various transplanting time in tobacco. Normal variety and male sterile line showed an average of 1. 6 and 29% natural crossing in the adjacent plantings, respectively. The natural crossing was highest in the adjacent planting, as expected, and less at the farther distance from pollinator plants. Plants transplanted in April 20th were higher in natural crossing than those of other transplanting time.

The contents of sulfur, sulfur-containing protein and amino acids of soybean seeds of 518 genotypes as well as their inheritance and selection efficiency in early breeding generation were measured to facilitate breeding for soybean with high sulfur-containing amino acids. Average seed sulfur content of 518 cultivars was 0.33%, and ranged from 0.20 to 0.45%, and that of 30 wild soybeans was 0.35%, and ranged form 0.19 to 0.62%. Correlation coefficients between seed sulfur content and sulfur-containing protein and amino acids were 0.924 and 0.974, respectively. Seed sulfur content was tended to be high in soybean genotypes with late maturity, seed coat bloom, or green cotyledon. Sulfur content had -0.312 correlation coeficient with sugar content and -0.384 with 100 seed weight. Seed sulfur content was inherited quantitatively, in which additive effect was greater than dominant one, and proportion of genes with positive effects was similar to those with negative ones. Estimated narrow- and broad-sense heritabilities were 0.75 and 0.88 for seed sulfur content, respectively. Heritability measured from selection in early breeding lines for high or low seed sulfur content was 60～62.5% or 50～62,5%, respectively. And selection for high sulfur content increased by 14.7～18.8%, whereas that for low one decreased by 8.8～15.6%, when compared to that of random population. Therefore selection in early generation seemed to be clearly effective.

Pre-sowing treatments of tobacco seeds (cv. NC82) were evaluated as a means of improving the speed of emergence, early seedling growth and uniformity of the seedlings. Seeds were treated through the use of polyethylene glycol 6000(PEG), solid matrix priming(SMP), chilling and dark-preincubati(DPI). Under the laboratory condition of 15, all the treated seeds germinated more rapid and the time to 50% germination(T50) reduced than control. Among the treatments, SMP was the best to reduce the T50 for germination. All the treatments did not affect the final germination percentage, while the chilling showed of little benefit for germination and T50. Under the greenhouse condition, seedling from SMP emerged earlier and more uniformity and also greater mean fresh and dry weight showed than other treatments. The advantage of T50 from SMP was affected more in temperature than in water content of Agro-Lig during the treatment.

Varietal difference in structural and physical characteristics of rice starch and interrelationships between these starch properties and the physicochemical components of rice grains were investigated for twenty four rice varieties, which were considerably different in amylose content, gelatinization temperature and gel consistency, to obtain the basic informations for diversifying the utility of rice grains and for developing various rice cultivars adaptable to rice food processing. Wave length of maximum absorbance for blue color reaction of starch-I complex was 520nm for glutinous rice and 560～600nm for nonglutinous rice. The higher amylose rice showed the longer wave length but there was considerable difference of the wave length among rice materials with similar amylose content. Varietal difference in frequency distribution of debranched starch molecules by isoamylase hydrolysis was largest in amylose fraction, the longest fraction(Fr. I), and was next bigger in intermediate fraction(Int.Fr.) and the ratio between short and long glucose chain of amylopectin fraction(Fr. III /Fr. II). The Fr. III / Fr II ratio was higher in glutinous rice than in nonglutinous one but it was considerably different among nonglutinous rice varieties without any connection with amylose content. The lower alkali digestible rice showed the longer half-hydrolysis time in acid solution. Both soft and hard gel rice varieties in gel consistency test revealed significant varietal difference of 50% acid hydrolysis time. The harder rice in gel consistency exhibited the less frequency of short branch fraction of amylopectin (Fr. III) and the higher amylose content. Twenty four rice varieties were cleary classified by upper two principal components contracted from structural or physical traits of rice starch and some physicochemical properties of rice grain by principal component analysis. The 1st and 2nd principal components can be characterized to components related with amylose and amylopectin structure respectively.

The experiment was carried out to investigate the changes in physicochemical properties of milled rice harvested in different year and stored for four to sixty four months. The fat acidity of milled rice increased sharply from four to sixteen months storage, and after then it was increased slowly to sixty four months. Amylose, magnesium, potassium content, and K/Mg ratio of milled rice were not changed by storage duration. Water absorption rates of milled rice at 21 and 77, and alkali digestion value were increased by longer storage duration. Difference of water absorption rate between rice samples was greater during initial forty minutes after soaking at 21 and with longer the soaking time at 77. Shorter gel length of rice flour was found with prolonged storage duration, while peak, minimum, cool, breakdown and setback viscosity of gelatinized rice flour on amylograph were increased along with increasing the storage duration. The volume expansion rate during cooking and degree of iodine coloration of cooking water were higher in the longer stored rice compared with shorter one, and the amount of soluble solid in cooking water was significantly decreased in rice stored longer period.

Bulbosum method, which haploids are developed by pollinating with H. bulbosum have been productive to be recommended as an effective method for the production of genetically stable normal barley hybrids. The purpose of this study is to investigate several characters of H. bulbosum, seed set and embryo development rate pollinated with H. bulbosum in order to establish a method for improvement of embryo development and to find conditions favoring plant development from the embryos cultured in vitro. Three lines of H. bulbosum used as pollinators: GBC(2), Spenish diploid(2) and var. Jaaska (4) were morphologically similar, having characteristically narrow leaves, narrow and long culms, long spikes and anthesis duration in comparison with H. vulgare. H. bulbosum, var. Jaaska(4) on being pollinated to barley cultivars, increased embryo formation by 8% and plant development in vitro by three times compared to the other diploid lines. the plants developed were not normal barley hybrids but had some H. bulbosum chromosomes uneliminated, indicating that the line was unstable as a pollinator to induce barley haploids.

Super-giant-embryo mutant line (Hwacheong-ge) with high nutritional quality was developed from Hwacheongbyeo, a Korean Japonica cultivar. Grain weight of brown rice of Hwacheong-ge line was lighter than of Hwacheongbyeo. However, embryo dry weight of the line was 3.22 times heavier than that of Hwacheongbyeo on the single grain base. Hwacheong-ge line showed higher protein(8.99%) than the original variety(7.39%), without changes in storage protein. In amino acid composition, lysine content was greatly increased in the mutant, while the contents of methionine, serine and tyrosine were slightly decreased as compared with the original one. Lipid content of Hwacheong-ge line was 1.5 times higher compared with that of Hwacheongbyeo. The contents of Vitamin Bl, B2, and E(-tocopherol) were also greatly increased in Hwacheong-geline. The grain yields of the mutant lines ranged from 69.2% to 78.8% compared with that of Hwacheongbyeo, 556kg /10a. Most of the mutant lines of M4 generation were homogeneous for growth characters, and some of them seemed to be readily applicable for farmer's field.

The metalaxyl seed-soaking treatment markedly increased the root-mat formation of the young rice seedling(8- to l0-day-old) for machine transplanting. This experiment was conducted to find out a possible rooting mechanism of the young rice seedling in relation to the exogenous metalaxyl seed-soaking treatment. The rice seeds of Hwaseongbyeo variety were soaked in the solution of metalaxyl for 24 hours at room temperature. Metalaxyl(25% wettable powder), a fungicide, was used at the concentration of 200ppm as a promoting substance on the root-mat formation of the young rice seedling. Seeding rate of the young rice seedling was 220g per seed tray(3060depth 3cm). Metalaxyl seed treatment was highly effective in root initiation and elongation of the young rice seedling in terms of root activity, the number and length of root, and amino acid content of roots. The exogenous metalaxyl application would also increase the chlorophyll content and photosynthetic rate in the young rice seedling. Those factors resulted in vigorous root-mat formation of the young rice seedling. In particular, alanine is a lead compound of metalaxyl which biochemically plays an important role in energy intermediate of the rice plant. Alanine conjugation with a glucose (N--glucoside) is probably the mechanism in enhancement of initiation and elongation of rice roots of young rice seedling.

This experiment was carried out at Chuncheon substation, Crop Experiment Station to investigate the effect of cold water irrigation on the growth and grain yield of rice in 1990. Irrigation of cold water (17) delayed 10 to 19 days of heading, and reduced about 17 to 31% of plant height in terms of culm and panicle length. Number of panicle per plant was decreased and / or increased by cold water irrigation. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Grain yield was increased but, straw weight was decreased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment. In general the dark brown and / or black colored kernel increased at cold water inlet but decreased percent of green kernel. Alkali digestible value increased and amylose content decreased at cold water inlet.

This study was conducted to obtain basic information for breeding materials on the oil quality improvement of perilla seeds. Oil contents and omega()fatty acid compositions of seeds were investigated to 317 varieties of domestic perillas. Oil contents of 317 perilla varieties ranged from 35.6 to 55.3 with 44.5% of varietal mean. The major omega fatty acids contained in the oil were oleic acid(-9) 15.2%, linoleic acid(-36) 13.9% and linolenic acid(-3) 63.1% in the mean value. Varietal variation of -9, 6 and 3 fatty acids ranged of 9.5～21.4%, 9.1～20.4% and 50.6～70.5% respectively. Unsaturated fatty acid were averaged 92.2% of seed oil in fatty acid composition. The ratios of -6 to -3 ranged of 0.13～0.34%(0.22% in mean value). The highest linolenic acid variety was Yecheonjong being 70.5%. The lowest variety in rations of -6 to -3 was Goseongjong being 0.13%. Oil content showed positive correlation with stearic acid and linolenic acid, while the negative correlation with oil content and linoleic acid. On the other hand, A significant negative correlation were showed between lionolenic acid and the ratios -6 / -3 fatty acid, saturated fatty acid. Saturated fatty acid was highly correlated with unsaturated fatty acid negatively being r=-0.723